farside161 - will try and post some diagrams and compenent numbers next week
adam666 - not yet, only exploding balloon, still a little scared, need to make a bubbler next, i also want to try connecting the pvm to a motorcycle ht coil with two hv outputs ... you may have seen a paper floating around for 2 or 3 years by a guy in coromandel saying he did that successfully (with a harley-davidson coil) . quite a few distributorless ignotion cars also have that set up, as does my 1966 vw (an aftermarket vw kit i paid us$180/kiwi$700 for when our $$$ was weak, now importable for kiwi$300, its got two dual coils)
thrival - padded out my project pages a little which should answer some questions for you
try bending the leaves of a feeler gauge to get an idea of stainless flexibility.
0.5mm/20thou" (the thinnest size you can get in a standard sheet (2400mmx1200mm / 10'x5' / 120" x 60" ) was too difficult to bend around a 25mm/1" pipe, 0.35mm/14-15thou" could be good and a bit stiffer
1mm gap is too tight a tolerance for a two+ plate design, but might work for a one plate .... a one plate with that gap would be very long, so you need to be able to source bulk shim from a 100yard roll
single plates present more of a mounting problem as i use the electrode posts to support the whole deel, but you could add more 'feet"/posts along the outer part opf the spiral
multiple plates in parallel might be easier
another alternative as a spacer would be weedeater/fat-fishing nylon wire
but it will be harder to get neater, because accurate positioning of the mounting holes allows no other alternative than a nice curved spiral with a very constant gap ... those holes must be accurate though ... when i made my plastic mockup, i just hand drilled the holes on a inkjet-printed and sprayglued template, and i could see where i wasnt careful enough when i rolled the mock-up up
the pegs are 6.25mm/.25" engineering plastic rods, easily obtainable
(damn you americans with your fractions and imperial measurements

)
ll do you a run as soon as my computer is free in about 10min
did the last two pictures in my spiral math page help you understand the script (posted last night)
ant
